Server Smoke Test

Start a fresh headless vllm engine:

bash

source ../vllm/.venv/bin/activate
HF_HUB_OFFLINE=1 \
VLLM_LOGGING_LEVEL=DEBUG \
VLLM_CPU_KVCACHE_SPACE=2 \
VLLM_HOST_IP=127.0.0.1 \
VLLM_LOOPBACK_IP=127.0.0.1 \
python3 -m vllm.entrypoints.cli.main serve Qwen/Qwen3-0.6B \
  --headless \
  --data-parallel-address 127.0.0.1 \
  --data-parallel-rpc-port 62100 \
  --data-parallel-size-local 1 \
  --max-model-len 512 \
  --dtype float16

Run the Rust server smoke test:

bash

cargo run -p vllm-server --example external_engine_openai_qwen -- \
  --handshake-address tcp://127.0.0.1:62100

The example starts the Rust OpenAI-compatible server on an ephemeral local port, connects to it via the async-openai Rust client, lists models, and then checks that a streamed chat completion yields the assistant role chunk, final-answer content chunks, and a terminal finish chunk. This example intentionally uses async-openai's standard typed create_stream API instead of BYOT, so it does not inspect the nonstandard reasoning_content field even though the Rust server may emit it for reasoning-capable models such as Qwen3. For reasoning behavior itself, use the vllm-chat smoke test or the vllm-server route tests.

IMPORTANT: Restart vllm each time you run the smoke test. The current headless engine cannot safely handle frontend reconnects after the client shuts down.